This invention relates generally to lift and slide devices and more particularly to multicylinder concentric lifts and slides utilized in various applications including manufacturing processes.
Typically, lift and slide devices are comprised of a single cylinder and a double acting piston, within the cylinder, that is integrally connected to a pushrod. This type of device is illustrated in U.S. Pat. No. 3,994,539, issued to Gottlieb on Nov. 30, 1976 entitled "Self Contained Activated Slide Apparatus and Method of Constructing and Utilizing Same", which is incorporated herein by reference. Hydraulic or pneumatic pressure is applied to either side of the piston, thereby creating a pressure differential across the piston. This pressure differential forces the piston and the pushrod to displace within the cylinder until the pressure on both sides of the piston is equal (i.e., until equilibrium is achieved). The displacement, or "stroke", of the pushrod is generally limited to the distance that the piston can displace within the cylinder. Thus, in order to increase the overall stroke for a particular application, two cylinder housings which contain the pistons have traditionally been attached to each other, or "piggy backed", to one another. This effectively doubles the stroke, since two devices are connected in series, however, the loads on each cylinder do not coincide. Accordingly, a moment is created which can result in distortion of the cylinder and impede displacement of the piston.
Alternatively, the overall stroke can be increased if lift or slide devices are attached to one another end to end, and in this configuration the forces on the cylinders do coincide. However, when this configuration is collapsed, it is double the length of the piggy backed configuration and therefore is less desirable in today's compact manufacturing facilities. To avert the above mentioned shortcomings, the present invention has a novel configuration that utilizes multiple cylinders and pistons. These components are preferably concentric to allow telescoping like actuation of multiple pistons.
Accordingly, one advantage of the present invention is that moments are not imparted upon the lift or slide device, thereby preventing distortion of the cylinder which could seize the piston.
Another advantage of the present invention is its ability to collapse into a very compact configuration by utilizing multiple concentric pistons and cylinders to create telescoping type actuation.
Yet another advantage of the present invention is the novel transport of a pneumatic or hydraulic medium into multiple cylinders via either stationary or moving coupling ports.
Additional objects, advantages, and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.